1. Field of Invention
The invention generally relates a rotary baler having a variable sized baling chamber. More particularly, the invention relates to such a rotary baler that further includes means for measuring the diameter and shape of a cylindrical bale, and at least one sensor configured to collect information regarding the diameter of a bale formed in the baling chamber.
2. Related Technology
Mechanical arrangements for detecting the size or the symmetry of a bale produced in a rotary baler have been proposed in U.S. Pat. No. 4,433,533 and FR No. 2 579 063 A. These references disclose two rolls that roll on belts that enclose the baling chamber. The position or the symmetry of the rolls is mechanically displayed to the operator of the tractor towing the rotary baler, as taught in FR 2 579 063 A, or is used for the automatic steering of the baler, as in U.S. Pat. No. 4,433,533.
EP 0 634 094 A teaches that the compact height of the bale can be detected using a spring in contact with the side flanks of the bale. This information is converted to an electrical signal using a potentiometer.
Other mechanical arrangements detect the size of the bale at a single measurement point. According to EP 0 287 156 A, the position of the tensioning pulley of the belt is mechanically transmitted to a micro-switch operating magnetically. As taught in EP 0 296 709 A, the position of the tensioning pulley is detected using a potentiometer. Additionally, DE 44 42 479 A discloses that the position of a movable sprocket during the formation of the bale can be detected using an optical sensor.
As a result of the dust generated, the mechanical components of the baler are likely to malfunction. Furthermore, only a single measurement point is available along the width of the bale, so that no reliable information is generated regarding the distribution of the diameter of the bale over its width.
U.S. Pat. No. 4,850,271 describes a rotary baler capable of measuring the diameter of the bale and then subsequently displaying this information. As disclosed, the measuring configuration includes three sensors positioned along the width of the baling chamber, each of which detects the tension in the belts of the baling chamber by use of a spring-loaded mechanism. The mechanism moves potentiometers that are connected to the display arrangement by means of a signal processor. An additional potentiometer detects the position of a tensioning arm of the belts. Relying on the three measurement values of the tension of the belts, the operator can detect the shape and any possible irregularities in the diameter of the bale and perform corresponding steering countermeasures in case that these are still possible. The detection of the diameter with respect to the position of the tensioning arm permits a determination of only the maximum diameter, while the information detected by the tension of the belts regarding the shape of the bale is relatively inexact. The reason for the imprecision is attributed to the fact that the tension of the belts is a function of not only the local dimension of the bale, but is also affected by bearing friction and mechanical properties that vary over the width of the bale, particularly the elasticity of the harvested crop. The mechanical elements of the sensors are exposed to a relatively dusty environment, become contaminated after a relatively short time and then the sensors operating capability is diminished.
DE 38 11 649 C proposes using multiple sensors distributed across the width of the flow of harvested crop, upstream of the baling chamber in a rotary baler, to determine the distribution of the harvested crop. These multiple sensors can also be used for an automatic sideways shifting of the baler and/or of the flow of the harvested crop. The sensors may operate in a non-contacting manner, for example, as capacity sensors or on the basis of light or ultrasonics. In each case, the harvested crop is detected before the baling process begins. The actual size of the bale is not detected.
Consequently, there is need to provide rotary baler capable of measuring the diameter and the shape of a cylindrical bale that is improved over the state of the art.